In a short, but important Dutch study, the added value of selective pre-enrichment for the detection of ESBL-producing enterobacteriacea (ESBL-E) was evaluated. The authors used their yearly prevalence study to shed more light onto the question if pre-enrichment (using a broth) might be equally improving the performance of ESBL-E detection, as it does with MRSA. While the literature on the topic might be controversial, this straightforward, well-performed study showed that direct culture failed to identify 25.9% (7/27) ESBL-E rectal carriers, which corresponds to 1.2% (7/562) of the screened population. While the overall rate of ESBL-E rectal carriage is not very high (4.8%) this study still demonstrates the importance of improving our methods to detect multi-drug resistant pathogens.

The authors did raise the question that the bacterial-load of the “extra” ESBL-E is probably very low, but conclude that it still may contribute to the spread of ESBL-E. Depending on the individual infection control approach to control ESBL-E, one might have to use both, direct culture and enrichment, since the later will prolong time-to-result by a day.

Reports of future studies on ESBL-E carriage need to be checked for their methods used, since “true rates” might be higher if only direct culture methods are used.

Kluytmans-van den Bergh et al. Rectal carriage of extended-spectrum beta-lactamase-producing Enterobacteriaceae in hospitalized patients: selective pre-enrichment increases the yield of screening. J Clin Microbiol Accepted manuscript posted online 20 May 2015, doi: 10.1128/JCM.01251-15